The invention relates to a ball throwing machine for ejecting tennis balls comprising an adjustable ball throwing mechanism, a microcomputer controlling the throwing mechanism for programmed stroke sequences, and a remote control unit attached to the microcomputer and having a touchpad keyboard for direct assignment of impact points of the balls and for command selection.
The tennis ball throwing machines gain more and more in importance as the level of the tennis play gets higher and the stroking techniques get more and more sophisticated. If a skilled player is to be trained in returning high speed balls, spinning or sliced balls or even lobs for a long time and precisely with the same impact point, then a highly qualified training partner is needed who is able to satisfy these requirements. In the computer age, this partner can be substituted by a sophisticated electronic ball throwing machine being able to eject balls of all stroke types with sufficient speed and accuracy.
In the known throwing machines, the stroke direction is to be adjusted by hand as, for example, with the pneumatic ball throwing machines. Therein, the ball moves forward in a narrow tube due to the high air pressure behind it and leaves the tube with a speed corresponding to the air pressure. The spinning or slicing of the ball can not be realized with this type of machines and, because of the continuous air compression, the operation is very noisy.
The advanced throwing machines apply a mechanical launching system having two rotating wheels which are driven in opposite directions. At the periphery of the wheel, special rubber coating corresponding to the ball shape are provided. The ball speed depends on the rotation frequency of the wheels. In some types of these electromechanical machines, the launching angle is adjusted sidewards in the horizontal plane using a motor driven mechanism. However, the adjustment in the vertical plane can be carried out only by tilting the whole ejecting mechanism by hand.
In some conventional machines, the angle of the launching can be varied in both planes, i.e. in horizontal and vertical directions, too, using motor driven mechanisms with electronic control. However, the electronic system used for the control allows only a very limited number of programmed strokes in a sequence, restricted to the most popular stroke sequences only, as the strokes to right-left, right-middle-left, base-line-dropshot, or some simple combinations of them.
The more up-to-date known machines are able to play longer stroke sequences, too, however, the number of the programmed strokes remains under 32 and the programming itself is very time consuming. In addition, they are not adapted for correcting the ball flight by programming and for controlling automatically the ball wear-out.
Another insufficiency of the known machines is the lack of remote control, which would allow for the player to program the game from his own place on the court. In fact, the remote control of the known machines is limited to the on/off switch of the main supply or to some very simple command as start the play, turn to the continuous play or stop. None of them, however, has an easy-to-use, battery-fed hand-held remote control unit for program data entering.